1 /* IEEE754 floating point arithmetic
2 * single precision
3 */
4 /*
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
7 *
8 * This program is free software; you can distribute it and/or modify it
9 * under the terms of the GNU General Public License (Version 2) as
10 * published by the Free Software Foundation.
11 *
12 * This program is distributed in the hope it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * for more details.
16 *
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 */
21
22 #include "ieee754sp.h"
23
ieee754sp_mul(union ieee754sp x,union ieee754sp y)24 union ieee754sp ieee754sp_mul(union ieee754sp x, union ieee754sp y)
25 {
26 int re;
27 int rs;
28 unsigned rm;
29 unsigned short lxm;
30 unsigned short hxm;
31 unsigned short lym;
32 unsigned short hym;
33 unsigned lrm;
34 unsigned hrm;
35 unsigned t;
36 unsigned at;
37
38 COMPXSP;
39 COMPYSP;
40
41 EXPLODEXSP;
42 EXPLODEYSP;
43
44 ieee754_clearcx();
45
46 FLUSHXSP;
47 FLUSHYSP;
48
49 switch (CLPAIR(xc, yc)) {
50 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
51 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
52 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
53 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
54 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
55 return ieee754sp_nanxcpt(y);
56
57 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
58 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
59 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
60 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
61 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
62 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
63 return ieee754sp_nanxcpt(x);
64
65 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
66 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
67 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
68 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
69 return y;
70
71 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
72 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
73 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
74 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
75 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
76 return x;
77
78
79 /*
80 * Infinity handling
81 */
82 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
83 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
84 ieee754_setcx(IEEE754_INVALID_OPERATION);
85 return ieee754sp_indef();
86
87 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
88 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
89 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
90 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
91 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
92 return ieee754sp_inf(xs ^ ys);
93
94 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
95 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
96 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
97 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
98 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
99 return ieee754sp_zero(xs ^ ys);
100
101
102 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
103 SPDNORMX;
104
105 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
106 SPDNORMY;
107 break;
108
109 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
110 SPDNORMX;
111 break;
112
113 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
114 break;
115 }
116 /* rm = xm * ym, re = xe+ye basically */
117 assert(xm & SP_HIDDEN_BIT);
118 assert(ym & SP_HIDDEN_BIT);
119
120 re = xe + ye;
121 rs = xs ^ ys;
122
123 /* shunt to top of word */
124 xm <<= 32 - (SP_FBITS + 1);
125 ym <<= 32 - (SP_FBITS + 1);
126
127 /*
128 * Multiply 32 bits xm, ym to give high 32 bits rm with stickness.
129 */
130 lxm = xm & 0xffff;
131 hxm = xm >> 16;
132 lym = ym & 0xffff;
133 hym = ym >> 16;
134
135 lrm = lxm * lym; /* 16 * 16 => 32 */
136 hrm = hxm * hym; /* 16 * 16 => 32 */
137
138 t = lxm * hym; /* 16 * 16 => 32 */
139 at = lrm + (t << 16);
140 hrm += at < lrm;
141 lrm = at;
142 hrm = hrm + (t >> 16);
143
144 t = hxm * lym; /* 16 * 16 => 32 */
145 at = lrm + (t << 16);
146 hrm += at < lrm;
147 lrm = at;
148 hrm = hrm + (t >> 16);
149
150 rm = hrm | (lrm != 0);
151
152 /*
153 * Sticky shift down to normal rounding precision.
154 */
155 if ((int) rm < 0) {
156 rm = (rm >> (32 - (SP_FBITS + 1 + 3))) |
157 ((rm << (SP_FBITS + 1 + 3)) != 0);
158 re++;
159 } else {
160 rm = (rm >> (32 - (SP_FBITS + 1 + 3 + 1))) |
161 ((rm << (SP_FBITS + 1 + 3 + 1)) != 0);
162 }
163 assert(rm & (SP_HIDDEN_BIT << 3));
164
165 return ieee754sp_format(rs, re, rm);
166 }
167